Identifying leaders—even defining what that role means [1]}—is
very difficult. Especially so, when probing the mechanisms that cause the
dynamical behaviors of aggregated agents. Beyond cells, these basic questions
also apply to bird flocking [2]}, fish
schooling [3]}, [4]}, caribou migration [5]},
and baboon foraging [6]}. A leader agent is often defined
as an individual that exerts more influence upon others than others influence
on upon it. That is, the role is fundamentally asymmetric. Previous
studies [7]}, [3]}, [4]}, [10]}, [11]}, [12]}, [13]}
proposed that, under this definition, pairwise analysis of trajectories can
assign leaders and followers under the working hypothesis that a change in
motion of the leader forecasts a change in motion of the follower. From
this, one interprets the change of leader motion as a candidate cause
that triggers the motion of followers.
